TENS Unit-Digital Dual Channel w/Timer Five Modes: Burst Continuous MRW Strength Duration and Bi-Pulse * Dual Channel with timer * Adjustable pulse rate and width * Pocket-size - easy operation * 3167A and 3166R include Digital Tens Unit reusable Electrodes (Pk/4) lead wires instruction booklet and carry case * Shipping Carton Size: 12 L x 10 W x 6 H